1. Field of the Invention
This invention relates to fluid flow valves, and more particularly, to a valve apparatus including first and second valve assemblies and a leak detection apparatus operable to detect a leak condition for one of the valve assemblies.
2. Description of the Prior Art.
In heating systems of the pilot ignition type, a pilot valve is energized in response to a request for heat, supplying pilot gas to a pilot outlet for ignition to establish a pilot flame. Once the pilot flame is proven, a main gas valve is operated to supply gas to a main burner apparatus for ignition by the pilot flame.
In such systems, conditions, such as the presence or absence of a flame at the pilot outlet, are frequently used to effect the sequencing operations provided by a control circuit of the system and to enable various checks to assure fail-safe operation of the system to prevent inadvertant operation of the valves. Thus, a leak condition for the pilot valve could interrupt the normal sequencing operations of the system as well as inhibiting certain of the checks which afford fail-safe operation of the system. Moreover, in the event the pilot valve is leaking, fuel will be continuously supplied to the pilot outlet, wasting fuel and producing a potentially hazardous condition.
Thus, it would be desirable to have a valve assembly which automatically responds to a leak condition for the fuel valve of the assembly and effects the shut down of the system to prevent operation of the valve for such condition.